I see delayed notifications was a problem on the S8 S9 S10 I have had all of those phones and I didn't have an issue, but as soon as I got the s20 it became an issue for me and it's been on going out for about 6 months or so.
I have tried all the items people wrote about from prior devices, but nothing seems to work.
What can I do to resolve it because it's really frustrating and causing me a lot issues.
This isn't something I've encountered on my phone's @silver13 and yes some people have experienced delayed notifications which can also be a result of a glitching sim card or network issues too.
As a process of elimination can you try your sim card in another phone and then see what happens.
A Samsung Experience Store or Samsung Service Centre can take a look.