Yes, but the parent comment you replied to was, I believe, referring to data leakage via DNS, not data leakage over HTTP requests. Two different things. What they were getting at is your ISP's DNS servers--and every DNS server hit along the path of resolution--know something about every request made by one of your devices when your devices route DNS through them. Assuming every request to
domain.com is encrypted, your ISP may not know
what you're sending to domain.com, but they do know
you are sending data to domain.com because DNS is in the clear by default. This has led a number of ISPs to capture this information and use it for purposes a customer often does not know about, understand, or may object to--such as selling that information, using it for injecting advertising or hijacking requests, and other actions. What's worse is that many ISPs (in the US, at least) ensure this behavior can occur by requiring customers to use gateways/routers that are locked down to ISP DNS servers, and many of these devices
prevent users from modifying the DNS servers used.
Encrypted DNS and devices like the Pi-hole provide end users a means of bypassing this behavior by avoiding ISP DNS servers entirely so even where you're trying to go isn't known by them.