So here are some references to official sources.
The 730 days per five years RO, including that calculating compliance is based on the previous five years (not the date a PR card was issued or expires, for example), is stated in the governing statutory provision, which is Section 28 IRPA and can be found here: https://laws-lois.justice.gc.ca/eng/acts/I-2.5/page-7.html#h-274598 and its application is discussed in the PDI (Program Delivery Instruction) "Permanent resident status determination" which is here: https://www.canada.ca/en/immigration-refugees-citizenship/corporate/publications-manuals/operational-bulletins-manuals/permanent-residence/card/permanent-resident-determination.html and also detailed in multiple operational manuals, which can be accessed in pdf form from links here: https://www.canada.ca/en/immigration-refugees-citizenship/corporate/publications-manuals/operational-bulletins-manuals/permanent-residence/card.html . . . these are ENF 23 - Loss of Permanent Resident Status; ENF 27 PR Card, and OP 10 Permanent Residency Status Determination . . . among many other sources.
The statutory provision that specifies a person cannot be granted citizenship if "they no longer meet the requirements" is Section 22(6) Citizenship Act which is here: https://laws-lois.justice.gc.ca/eng/acts/C-29/page-7.html#docCont . . . but to understand the nature and scope and application of that provision, it needs to be read and understood in context with other provisions and especially in conjunction with the eligibility requirements themselves (Section 5(1) Citizenship Act) as well as several other provisions, including the statutory provisions specifying prohibitions in particular.
For what is particularly relevant in the context you describe, the main thing is that if at any time before taking the oath a PR becomes inadmissible due to not complying with the RO, and thus becomes "subject to" a Removal Order, then that PR is NO LONGER eligible, no longer meets the requirements for a grant of citizenship.
Some of the requirements for a grant of citizenship are based specifically on facts as they exist on the date the application was made. Compliance with Canada Revenue tax filing rules, for example, is specifically based on tax filings during the five tax years preceding the tax year in which the application is made. For an application made today, or any other day in 2021, the relevant tax years are 2016, 2017, 2018, 2019, 2020, and that does not change no matter how long it takes to process the application. Another is the minimum actual physical presence requirement, which similarly is based on the previous five years, and of course no matter where the applicant is after applying, where the applicant was during the relevant five years, the "eligibility period," does not change. So the applicant who meets the physical presence requirement the day the application is made will continue to meet that requirement no matter how long it takes to process the application.
But many of the requirements depend on continuing circumstances and are thus subject to changes in fact. For example, a driving under the influence or domestic violence arrest the night before scheduled to take the oath can result in being prohibited and no longer being eligible to take the oath.
A PR abroad who returns to Canada in time to attend a scheduled oath ceremony who is reported at the Port-of-Entry, upon arrival, for failing to stay in compliance with the PR RO, and correspondingly issued a Removal or Departure Order, is similarly no longer eligible to take the oath.
If a lawyer has told you that it is no longer necessary to meet the PR RO after you have applied for citizenship, fire the lawyer and hire another. I say this as someone who consistently defers to the judgment of the professionals. But there is no doubt about the fact that an applicant for citizenship MUST continue to be in compliance with the PR RO . . . right up to the day the oath is taken.
If you are not yet clear what staying in compliance with the PR RO involves, go to the part of this forum which is specifically about Permanent Residency Obligations where there are a lot of topics about this. There are many discussions there in which not only are the laws, rules, policies, and practices cited and linked, but scores of official IAD (appeal) decisions with official accounts of how the RO has been applied in actual cases are cited and linked as well.
Like I said at the outset, it appears that if you return to Canada within the year or so, and especially if you do return by, say, June this summer, this is NOT a problem for you. But if you continue to remain abroad longer than that, best to get a clear understanding about how the PR RO works . . .
. . . bottom-line, any day you are arriving at a Port-of-Entry into Canada, for as long as you are still a PR (thus even if that is the day before you are scheduled to take the oath), you need to have been IN Canada at least 730 days within the five years immediately preceding THAT DAY, the day you arrive and are examined while entering Canada.
