Is there any harm if i unseal our "Site Page" content type inside our root site collection

[john john]

I am working on a sharepoint online tenant, and this tenant already has a built-in root site collection, where i have added my lists,pages, items, etc. Now i wanted to add some properties (site columns), to our modern pages. and to do so i need to add them inside the built-in "Site Page" content type. but when i click on the "Site Page" content type, by going to "Site Settings" >> "Site Content types" >> click on "Site Page", i realized that the "Site Page" content type is sealed and i can not add columns to it as follow:-

where there is not any settings links + the link to add columns to the site content is missing.

now to unseal it i can run this pnp commend:-

$cred = Get-Credential  
Connect-PnPOnline -Url https://***.sharepoint.com/ -Credential $cred
$ct = Get-PnpContentType "Site Page"
$ct.Sealed = $false
$ct.Update($true)

But is it a supported/recommended approach to unseal the built-in “Site Page” content type inside our root site collection? And if it is a supported operation then why this content type is set to be sealed by default?

[#2]

Mmm...Have you tried to add directly the columns to the Site Pages library so you can avoid the unseal?

[#3]

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@Juan Carlos González Martín wrote:
Mmm...Have you tried to add directly the columns to the Site Pages library so you can avoid the unseal?

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@Juan Carlos González MartínYes i already try to add the column to the "Site Pages" library, but the columns will not get added inside the "Site Page" list content type,while they got added inside the other list content types ("Wiki Page", "Web Part Page" &  "Repost Page")... i think this is because the "Site Page" list content type has its parent content type ("Site Page" site content type) sealed...

One note i have; if I create new site collection (also of type classic team site) the “Site Page” content type will be unsealed by default.. so not sure why my issue is only happening on the root site collection?

[#4]

@john john

I was in contact with Microsoft Support because we had the same issue. This feature was rolled out in 2018, actually all Modern Team and Communication sites should have been updated automatically. Apparently this didn't work everywhere (Microsoft couldn't give me any more info either). I was referred by support to the following article (https://gallery.technet.microsoft.com/office/Unseal-sealed-content-654ac401) with the note that this procedure is not supported.
However, Microsoft Support could not give me an alternative solution to the problem.