[OnePlus 8T ROMs, Kernels, Recoveries, & Other Deve] IAAxl:
My answer could be wrong, please correct me if you find any error or mistake!

Upgrade directly from OOS 11 based rom to OOS 13 based rom is not likely to work... I also had fastboot issue after update firmware from 11 to 12. No idea why.

But, for comparison:

OOS 11 stock partitions:

abl (2.2 MB), boot (101 MB), dtbo (8.4 MB), logo (8.0 MB), odm (35 MB), product (1.5 GB), recovery (105 MB), system (1.5 GB), system_ext (1.2 GB), vbmeta (8.2 kB), vbmeta_system (4.1 kB), vendor (1.6 GB), aop (205 kB), bluetooth (668 kB), cmnlib64 (512 kB), cmnlib (393 kB), devcfg (53 kB), dsp (67 MB), featenabler (90 kB), hyp (446 kB), imagefv (20 kB), keymaster (258 kB), modem (246 MB), multiimgoem (16 kB), qupfw (57 kB), storsec (20 kB), tz (3.2 MB), uefisecapp (127 kB), xbl_config (102 kB), xbl (3.5 MB), mdm_oem_stanvbk (4.9 MB), spunvm (356 kB), xbl_lp5 (3.5 MB), xbl_config_lp5 (102 kB)

OOS 12 stock partitions:

system (642 MB), system_ext (976 MB), product (14 MB), vbmeta_system (4.1 kB), abl (225 kB), boot (101 MB), recovery (105 MB), dtbo (25 MB), odm (199 MB), logo (344 kB), imagefv (1.2 MB), dsp (67 MB), bluetooth (438 kB), qupfw (57 kB), vbmeta (8.2 kB), vendor (960 MB), aop (205 kB), cmnlib64 (512 kB), cmnlib (393 kB), devcfg (57 kB), hyp (446 kB), keymaster (262 kB), modem (200 MB), xbl (4.0 MB), xbl_config (102 kB), storsec (20 kB), tz (3.2 MB), my_product (384 MB), my_engineering (348 kB), my_stock (740 MB), my_company (348 kB), my_carrier (348 kB), my_region (2.8 MB), my_heytap (717 MB), my_preload (348 kB), my_manifest (348 kB), my_bigball (637 MB), featenabler (90 kB), uefisecapp (127 kB), multiimgoem (16 kB), spunvm (356 kB), xbl_lp5 (4.0 MB), xbl_config_lp5 (102 kB), mdm_oem_stanvbk (4.8 MB)

OOS 13 stock partitions:

system (683 MB), system_ext (1.0 GB), product (13 MB), vbmeta_system (4.1 kB), abl (225 kB), boot (101 MB), recovery (105 MB), dtbo (25 MB), odm (199 MB), logo (344 kB), imagefv (1.2 MB), dsp (67 MB), bluetooth (455 kB), qupfw (57 kB), vbmeta (8.2 kB), vendor (966 MB), aop (205 kB), cmnlib64 (520 kB), cmnlib (401 kB), devcfg (57 kB), hyp (451 kB), keymaster (283 kB), modem (195 MB), xbl (4.0 MB), xbl_config (94 kB), storsec (25 kB), tz (3.2 MB), my_product (408 MB), my_engineering (348 kB), my_stock (764 MB), my_company (348 kB), my_carrier (348 kB), my_region (3.9 MB), my_heytap (845 MB), my_preload (348 kB), my_manifest (348 kB), my_bigball (976 MB), featenabler (90 kB), uefisecapp (127 kB), multiimgoem (16 kB), spunvm (356 kB), xbl_lp5 (4.0 MB), xbl_config_lp5 (94 kB), mdm_oem_stanvbk (4.8 MB)

You could notice that 12 and 13 have similar layout, while 11 is different.

In short, 12 and 13 has these partitions while 11 doesn't: "my_bigball my_carrier my_company my_engineering my_heytap my_manifest my_preload my_product my_region my_stock".

They seem to be the sub volume of the super partition. But I don't have further knowledge.

I recommand you to try backup your current data, do a fresh Android 13 install and then restore your data.

If you can manage to enter recovery or fastbootd, there is still hope to backup your data.

If not, you can still try to pull data partition out with QPST or MsmDownloadTool, but I've never tried and don't know how...

Anyway, wish you good luck.