They all do that and have for years. It's not safe to search for domains through any registrar.
Until after your domain is purchased, or you know who the current registered owner is, the domain you are shopping for is a closely guarded secret, more valuable than a master password.
Assume everyone (slack, msteams, your browser extensions, your firewall, your corporate VPN, your co-worker's electron apps) is snopping on you and will get a commission for leaking your domain to the fronting groups.
Domain squatters charge a minimum of that's at least $2000.