Comment # 39 on bug 1221531 from Bernd Speiser

(In reply to Paul Tannington from comment #38)
> (In reply to Wolfgang Rosenauer from comment #37)
> > Quick update:
> > All NSS packages I'm aware of now have crypto-policies disabled again.
> > Therefore locking or going back/or stay with 3.97 is not required anymore.
> > 
> > The relevant support will be added later again.
> 
> Just to confirm:
> Leap 15.5 updated mozilla-nss etc to 3.98-lp155.2.1 - all now appears OK,
> addons can be installed, forced signature verification succeeds.

same here, 3.98-lp155.2.1 just arrived through updater applet:
> zypper se -i -sx -t package MozillaFirefox mozilla-nss mozilla-nss-certs libsoftokn3 libfreebl3
Loading repository data...
Reading installed packages...

S  | Name              | Type    | Version              | Arch   | Repository
---+-------------------+---------+----------------------+--------+-------------------------------------------------------------
i+ | libfreebl3        | package | 3.98-lp155.2.1       | x86_64 | mozilla
i+ | libsoftokn3       | package | 3.98-lp155.2.1       | x86_64 | mozilla
i+ | mozilla-nss       | package | 3.98-lp155.2.1       | x86_64 | mozilla
i+ | mozilla-nss-certs | package | 3.90.2-150400.3.39.1 | x86_64 | Update
repository with updates from SUSE Linux Enterprise 15
i+ | MozillaFirefox    | package | 123.0.1-lp155.1.1    | x86_64 | mozilla

all extensions still active and verification OK.
Thanks for resolving the issue quickly.