System:
SPPB 3.8.6
Joomla 4.1.3
Helix Ultimate 2.0.8

Problem: .sppb-sp-slider-text has a fixed margin for left and right, which is forced by the pagebuilder "sppagebuilder.css" with !important.
When trying to change the margin with the pagebuilder, it does not take effect, because of the important rules.

sppagebuilder.css

.sppb-addon-sp-slider .sp-slider-content-align-center .sppb-sp-slider-image,.sppb-addon-sp-slider .sp-slider-content-align-center .sppb-sp-slider-text,.sppb-addon-sp-slider .sp-slider-content-align-center .sppb-sp-slider-title {
    margin-left: auto!important;
    margin-right: auto!important
}

A workaround at the moment is to force the margin with a custom style, within the addon.

Please report this to the developers.