public Mono<ResponseStatusCode> isAllowedToSendMessage(
            @NotNull Long groupId,
            @NotNull Long senderId) {
        return isGroupMember(groupId, senderId, true)
                .flatMap(isGroupMember -> isGroupMember != null && isGroupMember
                        ? isGroupMemberAllowedToSendMessage(groupId, senderId)
                        : isGuestAllowedToSendMessage(groupId, senderId));
    }
Note that a blocked user is never a group member
turms-service/src/main/java/im/turms/service/domain/group/service/GroupMemberService.java