according to this documentation page, TMTM v8.1 supports these versions of Oracle:
It is recommended to apply the latest Server Fixpack (8.1.00.425H), however, in order to assure the best support for Oracle 19C.
Please also pay attention to this note on the same doc page:
"Note that Oracle 12.2, 18, and 19 should use database type Oracle 12.1."
Other than that please know, that version 9.0 has been released a few weeks ago. The product got rebranded to "MainView Middleware Monitor" (MVMM), but it is still the same product and you can upgrade from TMTM 8.1 to MVMM 9.0 as normal.
Hope this helps.
Thank you Oliver
My pleasure Manoj.