The IP you normally would have communicated with is among the hijacked IPs, then you have exposure. The data you send to such IP is ending up in the hijacker's hands. As an end user, your only defense is to use end-to-end authenticated encryption between you and your intended other end-point. The authenticated part is very critical in this case.

A typical mitigation at the ASN level is to have allowlists of exactly which prefixes your downstsream ASN is expected and allowed to announce. I don't recall the name of this technique, and it's somewhat widely deployed, but definitely far from widely enough to secure Internet routing.

Individual end users don't have much of a chance to avoid BGP hijacking. You could continuously run traceroutes to your destination network, but then that gives you not much guarantee that individual TCP connections will take the same route as those ICMP packets.

By using encryption. That way if such attack occurs, the only negative effects is downtime, rather than data exposure.