SUMMARY
KCalc 24.02.2 had this ability, but later versions bring a new view and lost the ability of calculating things by keyboard just as a regular calculator.

STEPS TO REPRODUCE
1. Open KCalc
2. Don't use mouse, only use keyboard, press 2 + 2 enter + 2 enter * 3 enter

OBSERVED RESULT
KCalc will give an input error, or miscalculates the value

EXPECTED RESULT
KCalc calculates 2+2+2*3 sequentially and give 18, everything would be seen on the history tab too

SOFTWARE/OS VERSIONS
Linux: Arch-6.9.5
KDE Plasma Version: 6.0.5
KDE Frameworks Version: 6.3.0
Qt Version: 6.7.1

ADDITIONAL INFORMATION
KCalc History would look like in this example case:
6 × 3 = 18
4 + 2 = 6
2 + 2 = 4
This new bug renders KCalc unusable for my daily usage. As a workaround i have downgraded it to 24.02.2 and added it to IgnorePkg updates until this is fixed in the future.