Can't speak to the notice period, the Capts I know that did not take UPL were all given 2 months notice. They are using Force Majeure, Covid certainly qualifies as a Force Majeure by any definition.
End of service (EOS) is paid out at 3 different rates. This is by Saudi law. It is also not commonly known but has been the same way for 20+ years.
0-5 years of service = 1/3 EOS
5-10 years of service = 2/3 EOS
10+ years = Full EOS
Everyone I knew that had 5+ years were paid exactly or more than expected.