Hi Johnny Test!
Seems like your ITMS 8.5 RU4 database is restored to previous state where no DS 8.5 POST RU4 point fixes are installed, therefore managed clients with 8.5.5715 POST RU4 pf reporting to your ITMS 8.5 RU4.
Or this client computer is redirected from another ITMS 8.5 RU4 where DS Point fix is installed to this ITMS 8.5 RU4 where same DS point fix isn't installed? Or this is a Parent NS 8.5 RU4 where you see this expected version from Child NS replicated client computer?
Because in 8.5 RU4 release, Deployment Solution plug-in version is 8.5.5710
https://knowledge.broadcom.com/external/article/150933/what-are-the-released-itms-85-agent-or-p.html
Looks like previously you had installed DS point fix "DS_8.5_RU4_NC_CRE-9131_29Mar_1648572823216.zip" which version is 8.5.5715 from https://knowledge.broadcom.com/external/article/198337/cumulative-post-itms-85-ru4-point-fixes.html
Check registry on your ITMS 8.5 RU4 machine to see what Point fixes you had previously installed (Your ITMS 8.5 RU4 is with on-box SQL Server? or SQL Server is remote?)
To make expected version of DS agent, you will need to download this point fix "DS_8.5_RU4_NC_CRE-9131_29Mar_1648572823216.zip" and install it on NS 8.5 RU4 server, then expected version will be 8.5.5715
Best regards,
IP.