ST_B10 x 0.00341802 + 149

does not give you the final LST, this is for calibration only and the +149

Brightness Temperature (BT) in Kelvin, not the true LST.

To get LST, you need to correct the BT using surface emissivity

1- Landsat 8/9 thermal bands (TIRS Band 10) provide digital numbers (DN) or scaled surface temperature. The commonly used conversion formula:

BT​=ST_B10×0.00341802+149.0

Why BT ≠ LST?

Brightness Temperature (BT) is the temperature of a black body emitting the observed radiance. LST is the actual surface temperature, which depends on surface emissivity (ε).

You must apply an emissivity correction to estimate true LST: LST=BT/ (1+(λ⋅BT/ρ​​)⋅lnε)

Follow this PPT step by step and don't forget to calibrate the Landsat Bands

(SR_B1 to SR_B7 ) x 0.0000275 -0.2

(ST_B10 and ST_B11) x 0.00341802 +149

If you are using Landsat Collection 2 Level 2 surface temperature data, then this is the correct equation. The USGS has already processed this analysis-ready ST data. You can find the reference here:

https://www.usgs.gov/landsat-missions/landsat-collection-2-surface-temperature

Abdoune Hamou Thank you very much for taking efforts and making a PPT. Being a researcher however I feel compelled to hilight one error for future readers that the NDVI formula is using bands that are practically unavailable. Band 4 and 5 are surface reflectence bands hence are shortened as SR_B4 and SR_B5. ST_B10, and ST_B11 stand for surface temperature.

Thank you for your answer