Solar Cycle 25 (SC25) produced several major geomagnetic storms with distinctly different combinations of energetic electron precipitation (EEP) and solar proton event (SPE) forcing, providing a unique opportunity to investigate short-term ozone responses in the mesosphere-thermosphere system. We analyse four major storms occurring in May 2024, October 2024, November 2025, and January 2026 using Microwave Limb Sounder (MLS) observations and specified-dynamics WACCM-D simulations. Significant mesospheric ozone depletion was observed during all four events, with maximum ozone losses ranging from approximately 30 % to 80 %. Model-observation comparisons show that the dominant particle forcing varied substantially among the storms. The May 2024 superstorm was predominantly EEP-driven, whereas the October 2024 event was largely SPE-driven. The November 2025 and January 2026 storms represent mixed SPE-EEP cases, with a stronger proton contribution during January 2026. Negative ozone anomalies were consistently observed in the lower thermosphere during all four events. Although not reproduced by WACCM-D, their repeated occurrence suggests a lower-thermospheric response to major geomagnetic storms. Model simulations further reveal the indirect energetic particle precipitation (EPP) effect in the stratosphere, characterised by descending ozone depletion features dominated by EEP.</p> <p>The four SC25 storms demonstrate the value of combining satellite observations with chemistry-climate models to separate the contributions of SPEs, EEP, and atmospheric dynamics, while also revealing several areas where current representations of particle forcing and upper-atmospheric coupling can be further improved. Maintaining long-term observations of both EPP and atmospheric composition remains crucial for improving our understanding of atmosphere-space coupling during geomagnetic storms.