PR_END_OF_FILE_ERROR in Firefox on connection bypass

@adguard-bot commented on [Tue Jul 13 2021](https://github.com/AdguardTeam/AdguardFilters/issues/88260)

### Issue URL (Incorrect Blocking)
[https://www.torproject.org/](https://adguardteam.github.io/AnonymousRedirect/redirect.html?url=https%3A%2F%2Fwww.torproject.org%2F)
### Comment
Username: @Morku
> The issue `PR_END_OF_FILE_ERROR` always appears in first visit with Firefox. When I reload the page, it loads fine. It's then temporary fixed for this one AdGuard instance. I have noticed, that the HTTPS certificate is then "Let's Encrypt" instead AdGuard, but it's not in HTTPS Exclusion list. When I completely close AdGuard and reopen it, the issue recovers and I have to reload the page. It happens a second time, when you want start download e.g. `https://dist.torproject.org/torbrowser/10.5/torbrowser-install-win64-10.5_de.exe`. Disable filtering Ads, Stealth and Extension in AdGuard does not fix the issue. Reinstall HTTPS certificate also doesn't fix the issue. As workaround I had to add `torproject.org` in HTTPS exclusion list to fix it (or disable AG). This issue only exist in Firefox. I tested Edge Chromium and the page loads fine directly at first visit with AG enabled.

### Screenshots

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### System configuration

Information | value
--- | ---
AdGuard product: | AdGuard for Windows v7.6.1
Browser: | Firefox
AdGuard driver: | WFP
Stealth mode options: | Hide your search queries,
Send Do-Not-Track header,
Remove X-Client-Data header from HTTP requests,
Strip URLs from tracking parameters
DNS filtering: | server: `Cloudflare DNS-over-HTTPS`
filters: `"AdGuard DNS filter" with AdGuard Home`
Filters: | Ad Blocking:
AdGuard Mobile Ads,
AdGuard Base

Privacy:
AdGuard Tracking Protection,
AdGuard URL Tracking

Social Widgets:
AdGuard Social Media

Annoyances:
AdGuard Annoyances

Language-specific:
AdGuard Russian,
AdGuard German
Userscripts: | https://userscripts.adtidy.org/release/adguard-extra/1.0/adguard-extra.user.js