Some ur9849 is getting added

What url to what url are you migrating between?

Migrated it from mysterymonks.com to mysterymonks.com and mmstag.mysterymonks.com

This is happening in both the cases.

Did you use find/replace when transferring the site?

You can export just the database using advanced options and then use find/replace:
Find: url9849.mysterymonks.com
Replace: mysterymonks.com

There is no mention of this URL in the database. Here’s a screen recording

https://www.loom.com/share/21bb5fe248714e889f297f50223df0a9

In that case, it is either in a file somewhere or a plugin setting stored in the cloud. If that’s the case, the plugin cannot replace these values.