Why is the loading of apps and websites sometimes freezing on my Android phone?

I'm using AdAway in VPN mode to block all ads on 3 phones and sometimes apps and sites won't load at all or load slowly. I'm using 4G+ and getting 50 mbps download speed. Phones are Realme Narzo 50 5G and 2 Motorola Moto G50 5G. All sites and apps sometimes freeze during loading, like every 10 loads there is a freeze or very slow loading.