database disk image is malformed
This is a hint that something is wrong in your db file. Try to backup it into a new database using the .backup command (see https://www.guru99.com/sqlite-database.html).
Other than that, it seems that your new provider is a little rude not to allow larger db files. This might force you to start over from scratch from time to time, because database sizes of 100 MB and more are quite common even with moderately frequented servers (even if compression is turned on which is recommended).
Also talking about db performance, users reported that switching to postgres helps (but this needs support from the provider as well, it's probably only feasible on a dedicated server or a VM with root access).