Because they're betraying their own goals, as stated in their About page: “It is a service run for the public’s benefit. [...] Anyone who owns a domain name can use Let’s Encrypt to obtain a trusted certificate at zero cost. [...] Let’s Encrypt is a joint effort to benefit the community, beyond the control of any one organization.” Now they own they are under the control of a political organization.
Here is the paragraph Let's Encrypt added to their Subscription Agreement on 2026-06-04:
> You are not a person or entity that is:
> (a) located in, organized under the laws of, or ordinarily resident in any country or territory that is the target of comprehensive U.S. sanctions;
> (b) a prohibited or restricted party under U.S. or other applicable sanctions and export control laws and regulations;
> or (c) owned or controlled by or acting on behalf of anyone described in (a) or (b).
> You agree to use Let’s Encrypt Certificates and any services provided by or on behalf of ISRG in compliance with applicable U.S. export control and sanctions laws and regulations.