I think my competition is buying spammy backlinks for MY website

Does anyone know where .xyz and .biz high spam backlinks could have come from? Domain authority went down. Found quite a few. We don't buy backlinks so we're not behind it. Could someone Should I disavow them?

Examples:

ww25 (dot) foreva (dot) biz / page250 / (something)-near-me . html

faucet (dot) bitzfly (dot) xyz/ page250 / (something)-near-me . html WordPress ...