Louis Rossmann's consumer rights wiki has an article about this issue [1].
The TLDR is that support officially ended in 2023, but Microsoft's notice back then assured that the app would keep on working.
That notice has been edited this year to remove the assurance that the app would keep working, with no explanation and redirecting people to the free trial of their subscription offering.
It seems to be due to a Microsoft certificate expiring (in all apps) [2] and causing the app to lose editing capability because no new build of the 2019 suite will be released with an up-to-date certificate.
Everything is a subscription if you wait long enough.
Louis Rossmann's consumer rights wiki has an article about this issue [1].
The TLDR is that support officially ended in 2023, but Microsoft's notice back then assured that the app would keep on working.
That notice has been edited this year to remove the assurance that the app would keep working, with no explanation and redirecting people to the free trial of their subscription offering.
It seems to be due to a Microsoft certificate expiring (in all apps) [2] and causing the app to lose editing capability because no new build of the 2019 suite will be released with an up-to-date certificate.
[1]: https://consumerrights.wiki/w/Microsoft_Office_2019_and_2021...
[2]: https://learn.microsoft.com/en-us/microsoft-365-apps/mac/cer...