Microsoft converts Office 2019 for Mac perpetual licenses to read-only. versions
(consumerrights.wiki)
FWIW I just spent a couple of months testing a bunch of Office suites as a replacement for MS Office, and I settled on SoftMaker. The “Home” subscription (version without AI and reference features) is CAD $40/year (there’s also a free version with a few features removed) and it can do everything that MS Office can do, some things (like commenting in Word docs) it does better.