Experiencing Extremely huge ping spike using DSL

I'm having serious issues with my O2 DSL connection. While the internet works most of the time, I frequently experience very large ping spikes that cause noticeable lag and temporary freezes.

The issue is especially problematic during online meetings (Zoom, Teams, Google Meet, etc.), where audio and video occasionally freeze for several seconds. Sometimes I also notice delays while browsing or using other real-time applications.

The problem occurs intermittently throughout the day and does not seem to be tied to any specific device or application. The connection speed itself appears normal when tested, but latency becomes unstable, making video calls and other real-time activities unreliable.