Data from temporary logs will be moved (anonymized) to permanent logs. For me this reads as: once it is there, it is not your data anymore, not from Cloudflare Resolver for Firefox and not PII, so we can do ~whatever we wish.
IANAL but it looks like extreme weasel wording (and not even remotely GDPR compliant), there is nothing to violate.
IANAL but it looks like extreme weasel wording (and not even remotely GDPR compliant), there is nothing to violate.