I'm not sure I completely follow the linked PDF, but it seems to be suggesting exactly that:

    So, the big question for investors and depositors is this: how much duration risk 
    did each bank take in its investment portfolio during the deposit surge, and how 
    much was invested at the lows in Treasury and Agency yields? As a proxy for these 
    questions now that rates have risen, we can examine the impact on capital ratios
    from an assumed immediate realization of unrealized securities losses (see next page 
    for a full explanation of our methodology). That’s what is shown in the first chart: 
    again, SIVB was in investment duration world of its own as of the end of 2022, which 
    is remarkable given its funding profile shown earlier.

The argument seems to be exactly that SVB both had highly interest rate sensitive depositors and significant unhedged duration risk. Both led to correlated interest rate risk at SVB and both were unique in the US banking world.

Another key comment by Cembalest

    As shown below, being flooded with deposits from fast-money VC firms and other 
    corporate accounts at a time of historically low interest rates might have been 
    more of a curse than a blessing.

The chart shows that SVB's balance sheet expanded by 250% from 2019 to 2022 (compare JPM at ~40%, one of the lower banks listed and the next closest, Western Alliance at ~180% and Truist at ~150%).