You should have it by now.
I guess you have checked manually?
What's your csc?
Your firmware is from July last year.
You should now be on G986BOXB8DUE4
You can download it from here https://www.sammobile.com/samsung/galaxy-s20-plus/firmware/SM-G986B/BTU/download/G986BXXS8DUE4/15476...
Track usage, upgrade and get support with the My O2 appDownload My O2