I can't reach these websites from my Ziggo connection. From a KPN connection it works. There is no IPv6 on that site, just IPv4. The domain resolves tot the same IP adress on both providers. So no DNS issue.
MTR from Ziggo:
Start: 2022-04-27T19:10:20+0200
HOST: efok-desktop Loss% Snt Last Avg Best Wrst StDev
1.|-- _gateway 0.0% 10 0.4 0.4 0.4 0.5 0.0
2.|-- 10.255.166.1 0.0% 10 7.5 8.3 6.4 12.3 1.7
3.|-- gn-rc0002-cr102-et122-251.core.as33915.net 0.0% 10 20.2 14.0 10.7 20.6 3.8
4.|-- asd-tr0021-cr101-be150-10.core.as9143.net 0.0% 10 16.2 14.0 12.5 17.9 1.8
5.|-- nl-ams09c-ri1-ae51-0.core.as9143.net 0.0% 10 15.9 17.8 12.9 31.5 5.4
6.|-- 213-46-183-246.aorta.net 0.0% 10 12.7 12.8 11.8 13.4 0.5
7.|-- fra-eq5-02gw.voxility.net 0.0% 10 19.0 19.3 18.5 20.6 0.7
8.|-- ??? 100.0 10 0.0 0.0 0.0 0.0 0.0
MTR from KPN:
Start: 2022-04-27T19:08:24+0200
HOST: ### Loss% Snt Last Avg Best Wrst StDev
1.|-- _gateway 0.0% 10 0.3 0.3 0.3 0.4 0.0
2.|-- 195-190-228-91.fixed.kpn.net 0.0% 10 5.3 10.8 5.3 45.9 12.6
3.|-- ??? 100.0 10 0.0 0.0 0.0 0.0 0.0
4.|-- ??? 100.0 10 0.0 0.0 0.0 0.0 0.0
5.|-- ??? 100.0 10 0.0 0.0 0.0 0.0 0.0
6.|-- nl-ams09c-ri1-ae-5-0.aorta.net 0.0% 10 16.4 12.8 10.5 19.4 3.2
7.|-- 213-46-183-246.aorta.net 0.0% 10 12.3 10.5 10.1 12.3 0.6
8.|-- fra-eq5-02gw.voxility.net 0.0% 10 14.9 15.0 14.7 15.3 0.2
9.|-- fra-eq5-01c.voxility.net 90.0% 10 808.1 808.1 808.1 808.1 0.0
10.|-- 5.254.104.146 0.0% 10 48.3 49.3 48.3 54.7 1.9
11.|-- 40.po1.ar1.sof2.evolink.net 0.0% 10 51.5 51.7 51.4 52.2 0.3
12.|-- host-185-45-64-218.superhosting.bg 0.0% 10 51.4 66.1 49.8 170.0 38.5
13.|-- server26.superhosting.bg 0.0% 10 50.8 52.5 50.6 67.9 5.4
Both routes pass fra-eq5-02gw.voxility.net where the route from Ziggo dies, and from KPN contineus. This must some IP range block on voxility.net. Try contact superhosting if they can fix it. Maybe Ziggo can contact voxility.net.