Auto-braking is completely automated by GP4 itself, it's not part of the track design (except for possibly the CC-line, see below). Auto-braking tends to be very conservative so you do see this behaviour fairly often.
That said, the CC-line (which is part of the track) may have an effect on your performance if it is not optimal. But I looked at the Muralla circuit and the CC-line looks very good so not the issue here.
The real solution here is to press F1, to turn off auto-braking
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Intel NUC 8i3, 8GB RAM, MS Sidewinder Wheel