Never stack a VPN under Tor
The combination adds latency and reduces anonymity for most readers.
Common misconception: routing Tor traffic through a VPN adds an extra privacy layer and makes the reader safer. Reality: for the default reader, it usually makes things worse.
Reasons. First, the VPN provider now knows you are using Tor. Some VPN providers log this, some do not, but the fact that you are using Tor is now visible to a specific commercial party.
Second, latency doubles because you have added an extra hop. Tor is already slow enough. The VPN hop makes it slower for no security gain against the adversaries most readers actually face.
Third, some Tor guard-selection algorithms interact badly with VPNs. In some configurations you end up with a smaller effective anonymity set because your entry pattern is unusual.
The Bureau's position: use Tor Browser directly. No VPN. If your threat model actually requires a VPN under Tor (specific research or activism scenarios), you already know why you need it and this note is not for you.