Admob alternatives

Can any anyone advise for the admob alternatives?

Did the admob will place limit on ad serve if the published app link is shared and users are installing apps through clicking the shares link.

I have published 2 apps and i shared links to get installation. Now admob placed ads serving limit on it and showing no ads.

Can i use double ad components means admob and any other monitization component like startapp or applovin together in an app?

Please of any one can advise?