Exception: (22, 'Invalid argument') on Arch Linux

[amberdambey]

Apologies for asking here; I don't have a working Matrix client or IRC.

Invidious on my Debian server crashed, so I reinstalled it on an Arch Linux server instead. All seems well except for IPv6 rotator, which produces a strange error which doesn't seem to be documented anywhere:

[user@ArchServer smart-ipv6-rotator]$ sudo python smart-ipv6-rotator.py run --ipv6range=XXXX:XXXX:XXXX:XXXX::/64 [obfuscated for privacy]
[sudo] password for user: 
INFO:smart_ipv6_rotator.const:You have IPv6 connectivity. Continuing.
INFO:smart_ipv6_rotator.const:No cleanup of previous setup needed.
DEBUG:smart_ipv6_rotator.const:Debug info:
DEBUG:smart_ipv6_rotator.const:ranges --> ['2606:73c0::/32', '2404:f340::/32', '2001:4860::/32', '2a00:1450::/32', '2600:1900::/28', '2800:3f0::/32', '2606:40::/32', '2607:1c0:241:40::/60', '2607:f8b0::/32', '2620:120:e000::/40', '2c0f:fb50::/32', '2607:1c0:300::/40', '2605:ef80::/32', '2620:11a:a000::/40', '2404:6800::/32']
DEBUG:smart_ipv6_rotator.const:random_ipv6_address --> XXXX:XXXX:XXXX:XXXX:99c5:9062:cf2b:726d
DEBUG:smart_ipv6_rotator.const:gateway --> fe80::eaa2:45ff:feb8:65e8
DEBUG:smart_ipv6_rotator.const:interface_index --> 2
DEBUG:smart_ipv6_rotator.const:interface_name --> enp2s0
DEBUG:smart_ipv6_rotator.const:ipv6_subnet --> XXXX:XXXX:XXXX:XXXX::/64
DEBUG:smart_ipv6_rotator.const:random_ipv6_address_mask --> 64
ERROR:smart_ipv6_rotator.const:Failed to remove the configured IPv6 subnets 2606:73c0::/32,2404:f340::/32,2001:4860::/32,2a00:1450::/32,2600:1900::/28,2800:3f0::/32,2606:40::/32,2607:1c0:241:40::/60,2607:f8b0::/32,2620:120:e000::/40,2c0f:fb50::/32,2607:1c0:300::/40,2605:ef80::/32,2620:11a:a000::/40,2404:6800::/32
            May be expected if the route were not yet configured and that was a cleanup due to an error
            
INFO:smart_ipv6_rotator.const:Finished cleaning up previous setup.
Waiting for the propagation in the Linux kernel.
ERROR:smart_ipv6_rotator.const:Failed to configure the test IPv6 route. The setup did not work!
       Exception:
(22, 'Invalid argument')
[user@ArchServer smart-ipv6-rotator]$ 

Unlike #3 this happens consistently (no amount of retrying/restarting resolves this).

Installed package versions are as follows:

python-requests : 2.32.5-4
python-pyroute2 : 0.9.5-3
linux : 6.19.6.arch1-1

All installed from Arch repos.

Happy to provide more info if needed!