How did you determine that Bunny lacks IPv6?
The CDN certainly has it: https://bunny.net/blog/ipv6-returns-to-bunnycdn/
Depending on where I query from, OP's blog does have it as well:
# host jola.dev
jola.dev has address 37.19.207.38
jola.dev has IPv6 address 2400:52e0:1a04::1310:1
Seems @zorked is correct about some POPs simply lacking IPv6. I simply happened to hit one of those. Quite disappointing but I guess Bunny is on the cheap side and doesn't actually own or manage their network like big CDNs do.